By Alan McCoy from Dungeons & Dragons: Fundamentals
How to build challenging encounters against a Roper
Note: This has been prepared utilizing only the 5E Core Rules. The Roper can be found in the Monster Manual page 261.
One of the many dangerous beasts that is found primarily in the Underdark, these foul beasts have been sighted in other deep cave complexes that have no known connection to the underdark as well.
These creatures can mimic exactly the appearance of a stalagmite or a stalactite, though they prefer to utilize the stalactite disguise if there is an appropriate area from which they can do so.
If forced to use a ground or stalagmite approach, it will position itself in a chasm or some other natural barrier available.
A Roper will patiently wait completely still and indistinguishable from ordinary cave formations until it decides to attack.
Its main eye snapping open and long tendrils shooting out to grapple a target, pulling it in to feed upon the hapless victim.
The Ropers base is covered with literally thousands of sticky cilia, giving it a firm grip on the base service from which to pull.
Ropers have two different types of tendrils that they use on potential victims, the first are grasping tendrils, the second are weakening tendrils.
Grasping tendrils are for pulling, and the Roper may have up to six of these active at any given time but may activate and utilize others, should those be damaged or destroyed.
Weakening tendrils look much like grasping tendrils, but they have a sticky mucus that causes numbness and loss of strength in a victim touched by them.
A roper will consume its victim whole, and can digest almost every kind of flesh, metals, while other indigestible will be regurgitated after digestion of the flesh is complete.
The roper usually has an area set aside for its elimination/regurgitation and, if searched for, this detritus can yield valuable treasure.
Magical items consumed by the Roper have been known to survive the process, though they are often in need of some repair.
A roper is immune to the effects of its own mucus.
With proper tools and proficiency (an Alchemists kit for example), the mucus and the stomach acids – a powerful solvent – can turn into valuable commodities.
Individual Dungeon Masters will assign DC and amounts gatherable.
Step 1) Let’s Review what we know about the Roper
Ropers are creatures of exceptional strength and very high constitution.
They are very canny and have good judgement about the probability of a successful attack, possessing a Wisdom score of 16.
While they can manipulate objects and slowly move over difficult terrain, they are usually immobile in combat.
Their intelligence is below human average, but far above the instinctual or animal level.
Ropers move in a slow ciliated crawl, carefully picking their way around barriers and other obstacles.
They move 10 feet per round, and can climb 10 feet per round.
Ropers have Darkvision 60-Foot and a Passive Perception of 16.
If it remains motionless, the roper is indistinguishable from a natural cave formation.
I would require a Passive Perception role of 30+ to detect a roper without active searching.
I would also rule that False Appearance will create an exception to the Surprise Negation that some Feats (for example Alertness) grant.
The roper can extrude and manage up to six tendrils at a time.
These tendrils can attack a target up to fifty feet distant.
A Roper has multi-attack and can attack with up to four tendrils and make a bite attack in the same round.
Grasping tendrils can be damaged – AC 20, 10 Hit Points, Immunity to Psychic and Poison Damage.
Destroying a tendril deals no damage to the Roper itself, and the creature will merely activate a replacement tendril to use the next round.
Step 2) Determine the probable Strategy.
Ropers are cave dwellers’ worst nightmare.
An ambush predator with significantly above animal intelligence, and a significant sense of judgement.
Ropers prefer to lair in caverns with many other natural cave features.
When able, they prefer to pose as a stalactite that is roughly forty feet above the primary hunting surface.
The ideal hunting spot would be a narrow chimney in the ceiling that provides cover from those not directly below it.
Such ideal formations are rare, but “close” is better than nothing.
This position makes it difficult to attack it other than by spells or missile weapons.
If a Roper goes the Stalagmite route, it prefers a chasm or a physical barrier between it and the hunting zone.
When possible, the Roper wants to limit those that can physically attack it.
Whenever possible, the Roper will have a way to move out of the line of fire and escape further injury, even at the loss of a meal.
Step 3) Determine Tactics
Having detected a potential target, the roper will attack one individual within its range.
If it is at its preferred height (forty feet), this gives it a 20-foot cone for potential victims.
It prefers creatures that are not wearing heavy armor.
First, because such creatures are not as heavy and require less effort to lift.
Second because its attack is a grapple and creatures that are not wearing heavy armor are likely to be weaker and less able to escape from a grapple.
While it is often allowable to substitute Dexterity or Acrobatics for the skill challenge to escape from a Grapple, the Roper SPECIFIES a STRENGTH or ATHLETICS check.
Individual Dungeon Masters are of course free to overrule that restriction, but if they do so, they should drop the Challenge Rating and the experienced earned from fighting this creature.
The roper will use all four tendrils on a single victim.
Once a successful grapple is achieved, it will use its reel attack to immediately jerk the victim 25 feet closer to its mouth.
It is possible that the victim will now be providing 25% cover to those attacking from below.
In subsequent rounds, the Roper will secure its grip by grappling with more tendrils.
Note that the tendrils already in grapple just need to hold, and it can send down two more, to include one or more weakening tendrils.
The Monster Manual left the paragraph “Weakening Tendrils” effect undefined.
We can state that the creature must make a successful DC 14 Constitution save when hit by a weakening tendril, or lose 1d6 + 1 points of strength until the next short or long rest.
The Roper will preferably weaken its prey to helplessness prior to consuming it.
Any creature with a strength of zero will be affected with the UNCONSCIOUS condition, making every successful bite from the Roper an automatic critical hit.
Step 4) DM Tips and Observations
The Roper can lift a maximum of 540 pounds, this is more than enough for any single character.
The Roper should be given Tremorsense 120-foot to go along with its Darkvision 60-Foot.
The Roper should have its natural strength raised to 20, and the grapple handled as a CONTEST instead of a Strict DC.